The present invention relates to diaphragm pumps for pumping fluids. The invention is particularly applicable to a hydraulic-type diaphragm pump for pumping a liquid, and is therefore described below with respect to this application.
Many constructions of diaphragm pumps are known. Generally, such pumps include a diaphragm reciprocated by a drive for expanding and contracting a chamber for pumping the fluid, and a pair of check valves permitting the fluid to flow only in the direction of the inlet to the outlet by the reciprocation of the diaphragm. The known diaphragm pumps, however, are usually of fairly large construction. Moreover, when used for pumping a liquid, the priming operation, i.e. initially filling the pump with the liquid, is frequently rather difficult because of the compressability of the air initially within the pump.